1. Field of the Invention
The present invention relates to an image display apparatus that detects display problem areas in a display screen configured of multiple pixels, a control method thereof, and a computer-readable storage medium.
2. Description of the Related Art
Display apparatuses that display images (called simply “displays” hereinafter) generally have a structure in which pixels having light-emitting functionality are disposed in a vertical-horizontal grid form. For example, a full high-definition display is composed of 1,920 horizontal pixels and 1,080 vertical pixels, for a total of 2,073,600 pixels. In such a display apparatus, desired colors are expressed by the colors that are emitted from each of the many pixels mixing together, thus forming a color image.
If in a display apparatus a pixel malfunctions or a problem occurs in the light-emitting functionality thereof, that pixel will of course be unable to emit light and/or color properly. As a result, luminosity unevenness, color unevenness, or the like arises in the display, causing a significant drop in the quality of that display.
Meanwhile, as described earlier, approximately 2,000,000 pixels are present in a full high-definition display. However, it is easy to assume that maintaining uniform functionality in such a high number of pixels over a long period of time will be impossible. Generally speaking, the functionality of a pixel degrades over time. Furthermore, there are often individual differences in the degrees to which such functionality degrades. Accordingly, gaps between the functionalities of pixels become greater the longer the display is used and the higher the pixel count is, leading to an increase in pixels that malfunction or experience light-emitting functionality problems, which in turn leads to more marked luminosity unevenness and color unevenness appearing in the display.
Thus in order to prevent or reduce degradation in the display quality of the display, it is necessary to detect malfunctioning pixels or pixels having light-emission abnormalities, which are causes of display quality degradation, or to detect luminosity unevenness and color unevenness appearing in the display. Various techniques such as those described below have been proposed in order to detect malfunctioning display pixels such as malfunctioning pixels or pixels having light-emission abnormalities, or to detect luminosity unevenness and/or color unevenness.
For example, there is a technique that detects malfunctioning display pixels, luminosity unevenness and/or color unevenness, and so on using an external detection apparatus (see Japanese Patent No. 2766942; called “Patent Document 1” hereinafter). There is also a technique that detects the influence of degradation occurring over time using pixels, separate from pixels used for display, that are provided for detecting degradation occurring over time (for example, see Japanese Publication No. 3962309; called “Patent Document 2” hereinafter). In addition, there is a technique that detects malfunctioning display pixels using variations in the driving voltages and/or driving currents of the various pixels (for example, see Japanese Patent Laid-Open No. 6-180555; called “Patent Document 3” hereinafter). Furthermore, there is a technique that isolates malfunctioning display pixels, luminosity unevenness and/or color unevenness, and so on by a user of the display employing some kind of instructing apparatus (a mouse pointer or the like) on the display while that display is displaying an image used for detection (for example, see Japanese Patent Laid-Open No. 2001-265312 and Japanese Patent Laid-Open No. 2006-67203; called “Patent Document 4” and “Patent Document 5”, respectively, hereinafter). Further still, there is a technique that isolates malfunctioning display pixels, luminosity unevenness and/or color unevenness, and so on by a user of the display capturing an image on the display using a consumer digital camera and analyzing that captured image (for example, see Japanese Patent Laid-Open No. 2007-121730; called “Patent Document 6” hereinafter). Finally, there is a technique that isolates malfunctioning display pixels, luminosity unevenness and/or color unevenness, and so on by providing a detector on the rear of the display and using that detector (for example, see Japanese Patent Laid-Open No. 2007-237746; called “Patent Document 7” hereinafter).
However, the above techniques have had the problems described hereinafter.
Patent Document 1 discloses a technique that detects malfunctioning display pixels, luminosity unevenness and/or color unevenness, and so on using an external detection apparatus. With this detection technique, a test image is displayed in the display, and malfunctioning display pixels, luminosity unevenness and/or color unevenness, and so on are detected by obtaining the test image using an external detector and analyzing that image. This detection technique is problematic in that a significant external apparatus is necessary and many operations are required in order to set and adjust the external apparatus. Furthermore, applying such a significant external apparatus to a display that has already been shipped involves difficulties. Accordingly, this detection technique has not been suitable to detect malfunctioning display pixels, luminosity unevenness and/or color unevenness, and so on that increase as the display degrades over time.
Patent Document 2 discloses a technique that detects the influence of degradation occurring over time using pixels, separate from pixels used for display, that are provided for detecting degradation occurring over time. This detection technique is problematic in that a high amount of detection error will occur if the pixels used for display and the pixels that are provided for detecting degradation do not degrade uniformly over time. Furthermore, this detection technique is problematic in that it cannot detect gaps in the degradation over time between individual pixels used for display.
Patent Document 3 discloses a technique that detects malfunctioning display pixels using variations in the driving voltages and/or driving currents of the various pixels. This detection technique is problematic in that because it employs variations in the driving voltages and/or driving currents of the pixels, it is highly susceptible to the influence of electric noise. Furthermore, this detection technique is also problematic in that detection becomes difficult or there is an increase in detection error if the correlation between the driving voltages and/or driving currents and the luminosities of the various pixels breaks down.
Patent Document 4 or Patent Document 5 disclose techniques that isolate malfunctioning display pixels, luminosity unevenness and/or color unevenness, and so on by having a user of the display employ some kind of instructing apparatus on the display while that display is displaying an image that is used for detection. This detection technique is problematic in that it places a heavy burden on the user, and is also problematic in that because there is no guarantee that the user will properly specify the location of the malfunctioning display pixels, luminosity unevenness and/or color unevenness, and so on, the detection accuracy depends on the user.
Patent Document 6 discloses a technique that isolates malfunctioning display pixels, luminosity unevenness and/or color unevenness, and so on by a user of the display capturing an image on the display using a consumer digital camera and analyzing that captured image. As with the detection techniques disclosed in Patent Document 4 or Patent Document 5, this detection technique places a heavy burden on the user, and the detection accuracy thereof also depends on the user.
Patent Document 7 discloses a technique that isolates malfunctioning display pixels, luminosity unevenness and/or color unevenness, and so on by providing a detector on the rear of the display and using that detector. With this detection technique, the detector is provided on the rear of the display, and it is therefore necessary to introduce display light into the detector. There is thus a problem in that this technique cannot be used in a transmissive liquid crystal display. Furthermore, even if the technique is applied in a display aside from a transmissive liquid crystal display, such as a plasma display, the requirement to provide a light introduction path causes a drop in the numerical aperture, which can cause a drop in the display quality.